GlaxoSmithKline plc will return the rights to three drug targets to Anacor Pharmaceuticals Inc. but pay $5 million up front as it expands the deal around drugs zeroing in on a bacterial enzyme, malaria and tuberculosis.

GSK in June started two Phase IIb trials of GSK-052 in patients with complicated urinary tract infections and complicated intra-abdominal infections.

With the six-year deal, including an option to extend for two years, GSK took $10 million in equity in Anacor. Anacor received $12 million upfront and was eligible for development and regulatory milestones of up to $84 million.

The new deal gives GSK the option to indefinitely extend its exclusivity for LeuRS compounds for a payment of $5.5 million to $6.5 million. It also adds Anacor programs for tuberculosis and malaria.

Anacor and Medicines for Malaria Venture, a Switzerland-based not-for-profit, are working together on Anacor’s lead anti-malarial drug, AN-3661. They will continue development into Phase II, but GSK will have the option to exclusively license the program based on mid-stage proof-of-concept data.

GSK and Anacor have not disclosed the other three targets in the original deal, but GSK is returning the rights to those drugs.